Hemingway - Hemingway App makes your writing bold and clear.
LanguageTool - Free proofreading tool for OpenOffice, LibreOffice, Firefox, and Chrome.
Write App - No-distraction writing tool for your productivity.
Grammarly - Clear, effective, mistake-free writing everywhere you type.
ProWritingAid - For the smarter writer. A grammar checker, style editor, and writing mentor in one package.
WhiteSmoke - WhiteSmoke software products for writing and language. WhiteSmoke is a grammar checker, spell checker, style checker and more - in a single package. Also featuring translation software and English video courses.